Re: diffs between a buffer and the underlying file

[David Hansen <david.hansen@gmx.net>]

On 14 Sep 2006 08:19:28 +0200 Urs Thuermann wrote:

> I sometimes get into the following situation:  I open a file, make
> some changes, then I want to see the changes before saving the file.
> The best way to do this seems to be to set the region to the whole
> buffer, write the region to some temporary file, and run diff on the
> two files.  But I find this very unconvenient.
>
> I'd like to have a function in emacs which can be applied to a buffer,
> say buffer A, that opens a new buffer displaying all the changes
> between the buffer A and the disk file, opened in buffer A.
>
> Searching the emacs documentation I haven't found anything like this.
> Only functions for diff'ing two buffers or two files.

M-x apropos RET diff.*buf RET gives me (GNU Emacs 22) as the
first hit:

diff-buffer-with-file
  Command: View the differences between BUFFER and its associated file.

But maybe Emacs/20.7 is a bit old...

David